The nutrition of salmonid fishes. II. Studies on production diets

The body composition of salmonids raised in hatcheries is markedly different, both chemically and histologically, from that of wild fish (Wood et al., '57). Differences between arti ficial and natural diets were suggested as important causative factors. Several workers have compared specific hatchery diets to a wide array of wild organisms which form the com ponents of wild diets (Embody and Gordon '24; Schaeperclaus, '33; Phillips et al., '54, '56). There have been few de scriptive reports, however, in this field of animal husbandry and on the variations which exist in the composition and com pounding of production diets and the effects of these variations on body composition of hatchery fish.

The purpose of this paper is to describe the diets which are now used to raise salmonoid fishes in the Pacific Coast states, to present the variation which exists in the proximate an alysis of these diets and to relate the diet composition to the body composition of the hatchery product. The factors in strumental in producing the extreme differences in body com position between wild and hatchery fish Avere of particular interest.